https://ibb.co/d0My6NFg
https://ibb.co/W4Tr65ZB
What is the correct name of this bug? I have version 65, I can't update for certain reasons, I looked at many files with the words lava or geyser, but I haven't found one that fixes it yet. Even Lava pot fix meshes from 68 discussion not help. May be it is all about fog or ash weather and this bug has similar reason as hair bug whith ash storm weather?

Those are the effects of the
Those are the effects of the wrong alpha settings for the meshes. To put it shortly, alpha setting allow the blending of items with other visuals, like fog. I have noticed the problem with fires, to make an example. And it's probably the same with hair, although I am not sure, because I'm not certain of how ash storms function.
One can try to open the mesh in nifskope and change a few flags. However, when I tried doing so with fire, I got nowhere. I'm not sure if it's a limitation of the Oblivion engine or I just don't know enough about this.